Variable pitch propeller



Jan. 7, 1964 H. M- WALKER ET AL 3,116,794

VARIABLE PITCH PROPELLER 2 Sheets-Sheet 1 Filed Jan. 14, 1965 INVENTOR. BY M. WALKER 4 E. BECK #142 y CA Mu -f Ar TO/PNEY 1954 H. M. WALKER ETAL 1 VARIABLE PITCH PROPELLER Filed Jan. 14, 1965 2 Sheets-Sheet 2 INVENTOR.

HARRY M. WALKER BY CARL E. BECK M w d.

A T TO/PNEY United States Patent assignors of one-third to Walter 1). Whitney, San Carlos, Calif.

Filed Jan. 14, 1963, Ser. No. 251,380 3 Claims. (Cl. fill-160.47)

This invention relates to variable pitch propellers and more particularly to a variable pitch propeller adapted to be used on boats.

Heretofore, various structures have been evolved for permitting the pitch of a propeller to be changed so as to change the speed of the craft and also its direction. Examples of such variable pitch propeller structure are found in United States Patent No. 810,032 and Swedish Patent No. 25,567. Generally the structures of the cited patents include a sliding block, an oscillatably mounted propeller provided With a crank arm and a connecting pin between the sliding block and the crank arm to permit oscillation of the propeller upon axial movement of the block along the propeller shaft. One disadvantage of these prior art structures is that the size of the housing required to house the mechanism becomes too large to be practical. Another disadvantage is that the pitch changing mechanism is not efiicient and does not effect a smooth transition from one position to another.

The main object of the present invention is to overcome the disadvantages of prior art variable speed propeller structures.

Another object of the invention is the provision of a variable speed propeller structure wherein the pitch adjusting mechanism is housed in as small a space as possible so as to make the device practical.

Still another objectof the invention is the provision of a pitch varying mechanism that provides an efiicient mechanical advantage between the sliding block and the oscillatable blade so as to effect a smooth transition from one position of the blade to another.

Other objects and advantages will be apparent from the following specification and from the drawings.

FIG. 1 is a reduced side elevation view of a propeller structure including the pitch varying lever mechanism.

FIG. 2 is an enlarged longitudinal sectional view of the propeller supporting housing.

FIG. 3 is a cross section of the propeller supporting housing as taken along lines 33 of FIG. 2.

FIG. 4 is an end view of a propeller foot portion taken from the inside of the housing.

FIG. 5 is a perspective of the slide, and

FIG. 6 is a perspective of the block.

In detail, and first with reference to FIG. 1, the invention includes a drive shaft 1 which is rotatably supported on a bearing 2 and which extends outwardly of the hull (not shown) of the vessel. The outer end of the shaft 1 supports a housing generally designated 3 which is split about centrally of its length to provide a forward section 4 and a rear section 5. Said portions are releasably secured together by means of screws 6 (FIG. 2).

As best seen in FIG. 2 the outer end of drive shaft 1 is provided with a tapered portion 8 which receives the complementarily formed tail portion 9 of housing section 5. Said housing section 5 is fixedly secured to shaft 1 by means of nut 12 which is threadedly received on a reduced diameter terminal portion 13 of shaft 1.

Within housing 3 and slidably received on shaft 1 is a block generally designated 16 which is best seen in FIG. 6. Said block 16 is generally elongated and provided with an axially extending bore 17 through which shaft 1 extends. The example of the invention illustrated 3,116,794 Patented Jan. 7, 1964 in the drawings includes three propeller blades and for this reason the block 16 is formed at one end to a triangular cross section to provide three generally rectangular outwardly directed faces 18. The remainder of block 16 is generally cylindrical except that it is provided with flats 19 in coplanar continuation of faces 18. The block terminates at its forward end in a cylindrical end portion 20 which is internally threaded to receive threaded end 21 (FIG. 2) of an actuating tube generally designated 22. In the following description only one propeller and its connection will be described in detail.

Each face of block 16 is provided with a hole 25 which receives therein a relatively short pin 26 integral with and extending outwardly of one side of a generally rectangular elongated slide generally designated 27 (FIG. 5). The slide 27 is supported on the face 18 and is swingable about the pivot pin 26. Slide 27 is slidably received within a complementarily formed slot 35 formed in the inner end of the propeller blade generally designated 31. Each of the three propeller blades shown includes a blade portion 32, a journal portion 33, and a foot portion 34 (FIG. 3) within which the slot 30 is formed. The means for shifting the block 16 on shaft 1 will subsequently be described but at this point it will be noted from FIG. 2 that movement of the block 16 to the left carries pivot pin 26 with it thus causing the propeller blade 31 to rotate within the bearing portion 35 formed in the housing 3. During this movement the slide 27 moves outwardly relative to the slot 30 in propeller blade foot 34 (FIG. 4).

In FIG. 2 the slide 27 is shown in a position at right angles to the central plane of the shaft 1 and such position may be considered substantially neutral in that the angle of the propeller blade is such that the least amount of propulsion effort is transferred to the propellers. As the block 16 moves to the left, the propeller blade oscillates in a clockwise direction (FIG. 2) increasing its angle of attack and augmenting its thrust in the water. The full forward position is indicated schematically in FIG. 2 and corresponds to the position of the blades exerting the greatest amount of propulsive effort.

Upon movement of the block 16 to the right as seen in FIG. 2, the blade oscillates in a counter clockwise direction from the neutral position shown in full line thereby effecting reversal of the angle of the blade causing the craft to be driven in a reverse direction. It will be apparent that the angle through which the slide 27 moves to achieve a full reverse position need not be as great as that required in a forward direction since the speed required in reverse is substantially lower than that required in forward.

As best seen in FIG. 3 the central axis of the propeller blade 31 is offset with respect to the central axis of the shaft 1 so that said axes do not intersect. Thus, the axis of the propeller blade may be considered parallel to a particular plane containing the central axis of the shaft 1. The axis of the propeller never intersects said particular plane. It will also be noted from FIG. 3 that the pivot pin 26 is on the opposite side of said particular plane of shaft 1 from the axis of propeller blade 31. This arrangement in which the propeller blade is offset and the pivot pin is also offset on the opposite side of the axis of the shaft achieves an extremely smooth operation insofar as the coaction of the block 16 and the foot 34 of propeller blade 31 is concerned. This smooth action is attributable to the fact that a relatively long lever arm, in effect, exists between pivot pin 26 and the axis of propeller blade 31. This long lever arm with its attendant mechanical advantage results in a smooth pitch adjustment operation since the propeller blade is moved by the block and not vice versa. Furthermore, it will be noted that the arrangement shown and particularly the interposition of the slide 27 between the block 16 and the propeller blade 31 is done in a minimum amount of space so that the size of the unit does not become unwieldy.

Referring again to FIG. 1, it will be seen that the inner end of tube 22 is supported in a bearing 40. In order to effect the desired translatory movement of block 16 relative to shaft 1 bearing 40 is connected by pivot pins 41 to a yoke 43 which in turn is secured to the lower end of an elongated vertically disposed operating lever 42. The lower ends of the legs of the yoke 42 are provided with pins 45 to which are pivotally connected the corresponding ends of a pair of links 46 which extend from said pins 45 to pivot pins 47 carried by the bearing 2 which rotatably supports the main shaft 1. Upon swinging movement of the lever 43 in the direction indicated by the arrow in FIG. 1 it will be seen that hearing 40, and therefore tube 22, will be moved to the left so as to increase the pitch angle of the propeller in a forward direction thereby effecting a greater forward speed. Upon swinging movement of the lever 43 in the opposite direction, the propeller blades will be moved toward the reverse position. It will be understood, of course, that the bearing 2 which rotatably supports main shaft 1 is fixedly secured as by a clamp device 50 to any fixed portion of the vessel such as indicated at 51.

Adjustability of the maximum forward pitch may be effected by providing a bushing 54 which is rotatably supported in movable bearing 40 in which the threaded end 55 of tube 22 is received. A lock nut 56 may be provided to fixedly secure tube 22 to bushing 54 in the desired adjusted position.

If it is desired to hold the lever 43 in any position, such as neutral, an arm 60 rigid with each leg of U- shaped yoke 42 may be provided and may cooperate With a spring urged pin such as indicated at 61 in FIG. 1 for holding the linkage in said neutral position subject to its being changed by sufficient force being exerted on lever 43 to move it past spring urged pin 61.

Referring again to FIG. 3 it will be understood that there is very little tendency for the propeller blades to drive the block although the movement in the reverse direction may be readily effected. This tendency Br the device to be irreversible is advantageous in that a load is not impressed on the lever 43 by the propellers although the movement of the block 16, in order to change the pitch of the propeller blades, may be carried out with facility.

In the interest of safety it is desirable to arrange the pitch changing mechanism so that there is no possibility of the propellers shifting accidentally into reverse position. This is readily achieved by inserting a compression spring 64 around tube 22 between the housing 4 and the forward end of block 16 as best seen in FIG. 2. Movement of the mechanism toward reverse position must therefore be against the urgency of said spring 64 which is desirable.

The above very specific description of the preferred embodiment of the invention should not be taken as restrictive thereof, since various modifications in design may be resorted to by those skilled in the art without departing from the scope of the following claims.

We claim:

1. A variable pitch propeller structure comprising:

a rotatably supported propeller shaft,

a housing mounted on said shaft for rotation therewith,

a propeller blade mounted in said housing with its axis in a plane at right angles to said shaft,

means in said housing supporting said blade for oscillation about said axis to different positions relative to said plane,

a block slidably supported on said shaft for movement to different positions corresponding to said different positions of said blade,

said blade being provided with a groove extending radially of its axis,

a slide reciprocably received in said groove,

pivot means pivotally connecting said slide to said block for pivoting said slide about an axis parallel to the axis of said blade,

whereby movement of said block axially of said shaft swings said slide about the axis of said pivot means for oscillating said blade about its own axis,

the axes of said blade and said pivot means being on opposite sides respectively of the axis of said shaft.

2. A structure according to claim 1 wherein said pivot means comprises a pin integral with said slide and received in a hole in said block.

3. A three bladed variable pitch propeller structure comprising:

a rotatably supported propeller shaft,

a housing mounted on said shaft for rotation therewith,

three propeller blades mounted at their corresponding ends in said housing for movement therewith and for oscillation to different corresponding positions about coplanar axes apart, and in a plane perpendicular to the axis of said propeller shaft,

a block slidably supported on said shaft for movement to different positions corresponding to the different positions of said blades,

said blades being provided at said corresponding ends with grooves extending radially of the axes of said blades,

a slide reciprocably received in each of said grooves,

pivot means pivotally connecting said slides to said block for pivoting said slides about axes parallel to the axes of their corresponding blades,

the axis of oscillation of each blade and the axis of the corresponding pivot means being on opposite sides of the axes of said shaft.

References Cited in the file of this patent UNITED STATES PATENTS 617,373 Truscott Jan. 10, 1899 676,738 Edwards June 18, 1901 810,032 Brown Jan. 16, 1906 885,038 Gnaegy Apr. 21, 1908 1,891,384 Gillis et al. Dec. 20, 1932 2,269,833 Upton Jan. 13, 1942 FOREIGN PATENTS 25,567 Sweden Sept. 26, 1908 29,829 Great Britain Dec. 21, 1909 268,690 Italy Oct. 25, 1929 614,731 Great Britain Dec. 22, 1948 

1. A VARIABLE PITCH PROPELLER STRUCTURE COMPRISING: A ROTATABLY SUPPORTED PROPELLER SHAFT, A HOUSING MOUNTED ON SAID SHAFT FOR ROTATION THEREWITH, A PROPELLER BLADE MOUNTED IN SAID HOUSING WITH ITS AXIS IN A PLANE AT RIGHT ANGLES TO SAID SHAFT, MEANS IN SAID HOUSING SUPPORTING SAID BLADE FOR OSCILLATION ABOUT SAID AXIS TO DIFFERENT POSITIONS RELATIVE TO SAID PLANE, A BLOCK SLIDABLY SUPPORTED ON SAID SHAFT FOR MOVEMENT TO DIFFERENT POSITIONS CORRESPONDING TO SAID DIFFERENT POSITIONS OF SAID BLADE, SAID BLADE BEING PROVIDED WITH A GROOVE EXTENDING RADIALLY OF ITS AXIS, A SLIDE RECIPROCABLY RECEIVED IN SAID GROOVE, PIVOT MEANS PIVOTALLY CONNECTING SAID SLIDE TO SAID BLOCK FOR PIVOTING SAID SLIDE ABOUT AN AXIS PARALLEL TO THE AXIS OF SAID BLADE, WHEREBY MOVEMENT OF SAID BLOCK AXIALLY OF SAID SHAFT SWINGS SAID SLIDE ABOUT THE AXIS OF SAID PIVOT MEANS FOR OSCILLATING SAID BLADE ABOUT ITS OWN AXIS, THE AXES OF SAID BLADE AND SAID PIVOT MEANS BEING ON OPPOSITE SIDES RESPECTIVELY OF THE AXIS OF SAID SHAFT. 